The present invention relates to a close-up, macro-or micro-photographic lens system, and it relates more specifically to a lens system having an F-number of about 1:2.8 and a view angle of about 24.5.degree., in which various aberrations are well compensated for from an infinite distance photographic position to a short distance photographic position of unity magnification.
Conventionally, there have been provided lenses for use in short distance photographing, which are so called "micro- or macro-lenses". Since such lenses are inherently designed so that an image forming performance becomes best in the short distance photographing condition, the aberration compensation in the infinite distance photographing condition is unsatisfactory in comparison with other general lenses. Also a lens having a floating function is well known for the purpose of correcting change in aberration due to the change of the photographic distance.
Although some lenses of such type having the floating function have a higher brightness with an F-number being about 1:2.8, a focal length thereof is relatively short and a maximum magnification of the lens system per se is about 0.5 times. Therefore, if a unity magnification photographing is desired, it is necessary to use an adaptor such as a close-up ring. Also, in case of lenses having no floating function, it is impossible to increase a brightness, that is, an F-number thereof is about 1:3.5 to 1:4; and the maximum magnification would fall in the range of 0.25 to 0.5 times.